/*
 * Copyright [2013-2021], Alibaba Group Holding Limited
 *
 * Licensed under the Apache License, Version 2.0 (the "License");
 * you may not use this file except in compliance with the License.
 * You may obtain a copy of the License at
 *
 *    http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS,
 * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 * See the License for the specific language governing permissions and
 * limitations under the License.
 */

package com.alibaba.polardbx.executor.calc;

import com.alibaba.polardbx.executor.chunk.BlockBuilder;
import com.alibaba.polardbx.executor.chunk.Chunk;

public interface Aggregator {
    /**
     * @param groupId id of the target agg group, sortAgg and windowExec may use 0
     * <p>
     * Accumulate a value into target group
     */
    void accumulate(int groupId, Chunk inputChunk, int position);

    /**
     * write aggregated result to the block builder
     */
    void writeResultTo(int groupId, BlockBuilder bb);

    /**
     * Append a new group with initial value, may be null, 0 or something else
     */
    default void appendInitValue() {
    }

    /**
     * Reset the group to its initial value
     */
    default void resetToInitValue(int groupId) {
    }

    /**
     * @param capacity estimated group size
     * <p>
     * Init the aggregator
     */
    default void open(int capacity) {
    }

    /**
     * Estimate the memory consumption
     */
    default long estimateSize() {
        return 0;
    }
}
